1. Field of the Invention
The present invention relates to pneumatic couplings wherein O-rings are recurrently moved across the mouths of ports. Many of those pneumatic couplings are used as on-off valves as well as quick connect-disconnect couplings.
2. Description of the Prior Art
In pneumatic couplings, which are used as on-off valves as well as quick connect-disconnect couplings, O-rings are recurrently moved back and forth across the mouths of ports. As pointed out in lines 49-51 of column 3 of my U.S. Pat. No. 3,127,149 for Valved Hose Couplings which was granted March 31, 1964:
"O Rings 38, 39 * slidably, but, neverthess, snugly engage the outer surfaces of the barrel 1 so as to provide seals".
The O-ring 38 recurrently passes over the mouths of ports 10 as a "valve forming sleeve 34" (Col. 3, L. 44,45), which is "internally undercut to provide two axially spaced narrow grooves 35,36" (Col. 3, L.46,47) for that O-ring and an O-ring 39, is "shifted to `open` position, as shown in FIG. 2" (Col. 4, L. 61) or to "a closed position" (Col. 4, L. 71).
In pneumatic couplings wherein the ports are of constant diameter throughout their lengths, the edges of the mouths of the ports tend to abrade the O-rings, as those O-rings recurrently engage those edges--even where those edges are carefully machined and ground to eliminate burrs and rough spots. Efforts have been made to chamfer or otherwise reduce the sharpness of the edges of the mouths of the ports in pneumatic couplings; but even where the edges of ports have been chamfered or have otherwise had the sharpness thereof reduced, the abrading of the O-rings by those edges seriously limits the life of those O-rings. The replacement of some O-rings within pneumatic couplings can be very difficult, timeconsuming and expensive; and some users discard pneumatic couplings rather than try to replace the O-rings therein.